Different enzymes are categorized as a specific type of hemicellulase--a glucanase, a xylanase or a mannanase, for example--based on an ability to catalyze the hydrolysis of heteropolysaccharides composed of glucan, xylan or mannan, respectively. It is known that enzymes that effect hydrolysis of mannans, such as a galactan or a glucomannan, are produced by various microorganisms, including bacteria and fungi, and that they also occur in some animals and in numerous plants. Among the microorganisms that produce such mannanases are species of Aeromonas, Aspergillus, Streptomyces, Rhodococcus and Bacillus. See 160 METHODS IN ENZYMOLOGY Part A, Sect. II (1988).
Hemicellulases have been employed commercially in the processing of coffee, chocolate, cocoa, tea and cereals. The primary advantage gained by using a hemicellulase in this regard is a reduction in solution viscosity which allows for more inexpensive processing of food products. Thus, hemicellulases are used to clarify fruit juices, to reduce the viscosity of slurries or purees, to liquefy certain cell wall solids, and to modify taste. But if the available energy content of human food and animal feed products could be increased, particularly in animal feed, there would be opportunities for cost savings. The successful use of glucanase-treated barley as a corn substitute in avian diets is one such example. See Feedstuffs 62: 10 (1990).
Hemicellulosic materials such as alfalfa, coconut residue, guar, locust bean gum, carob bean gum, cassava, copra and soybeans are common constituents of food and feed products. Soybean derivatives comprise a substantial proportion of the ingredients of tofu for human consumption, for example, and soybean protein is used in many feeds for dogs and cats, swine, fish and chickens. Soybean meal may comprise as much as 25% of the feed for baby chickens. The feed rations for chickens, such as broilers, are complex mixtures, formulated from a number of components on a least cost basis. The rations are required in very large volumes. As a result, costly storage facilities for the feed components are necessary for the blending operations. The feed components are blended to provide an optimal nutritional mixture of protein, essential amino acids, minerals, vitamins and calories (that is, an energy source). Soybean meal has been found to be a preferred concentrated source of protein with amino acids and, while not considered a primary energy source such as yellow corn, it supplies about 20% of the energy requirements of broiler chickens.
Although soybean meal provides some carbohydrates and oils which yield energy, approximately 10% of its total carbohydrate content is comprised of galactans and pentosans. These carbohydrates are not absorbed to any appreciable degree by monogastric animals as the animals are unable to digest them rapidly enough to obtain the appropriate monosaccharide for further biochemical oxidation. One approach to increasing the energy content of soybean meal would be to reduce the galactans and pentosans to low molecular weight oligosaccharides or monosaccharides like glucose or similar carbohydrate components which can be more easily metabolized by monogastric animals.
A need therefore exists for a way to increase the available energy content of the hemicellulosic component of food and feedstuffs by converting mannan-containing hemicellulose components therein into lower molecular weight carbohydrates which can be metabolized by monogastric animals.